Electromagnetic relays



Nov. 4, 1958 B. 1.. \JVIJKMAN 2,859,301

' ELECTROMAGNETIC RELAYS Filed Sept. 7, 1955 INVENTOR.

BENGT LUDVIG WIJKMAN HM/MW ATTORNEYS United States Patent 2,859,301 ELECTROMAGNETIC RELAYS Bengt Ludvig Wijkman, Stockholm, Telefonaktiebolaget L M Ericsson, a corporation of Sweden Sweden, assignor to Stockholm, Sweden,

The present invention relates to electromagnetic relays and more particularly to a relay comprising an electromagnet with an armature which, when the relay is operating, moves an operating strip, displaceable in its longitudinal direction between two end positions, said operating strip being arranged during its movement to'operate upon substantially stiff, movable contact members for closing and opening respectively of fixed contact members, arranged along the length of the operating strip.

The purpose of the invention is to produce a relay for use, for instance, in railway signal systems, and its design and construction is such, that at least the principal part of the relay, comprising the electromagnet with its armature and the fixed contact members as well as the relay frame, can when fabricated in series be made entirely unchanged irrespective of the contact functions (make and break contacts) which are desired in the finished relay, while the disposition of the fixed contact members for difierent sets of contacts can either be determined by using an operating strip, having movable contact members which are specially located with regard to said disposition or by designing the operating strip in such a way, that the movable contact members can optionally be placed in the strip in order to obtain the desired contact functions.

The relay according to the invention is, in the first place, characterized by the fixed contact members having the shape of a torsion spring, which are substantially L-shaped, each having the end of one arm, the fastening arm, firmly fastened against torsion in relation to the relay frame and having the free end of the other arm, the contact arm, formed to co-operate with pertaining movable contact members and, finally, having the fastening arm turnably supported in relation to the relay frame adjacent to the contact arm so that the contact arms of the fixed contact members can swing out from a neutral position in both directions of motion of the operating strip while producing a counter force due to the torsional action in the fastening arms, whereby the movable contact members consist of rigid pins or equivalent, stifiiy arranged in the operating strip.

The use of fixed contact members in the shape of torsion springs according to the above is particularly important for the invention, as the fixed contact members will take particularly predetermined neutral positions at the same time as they ensure desired contact pressure when swinging out in both directions, by means of which their function becomes fully uniform in break and make contact functions. Thus, only by selecting the position of the movable contact members, the fixed contact members can arbitrarily be used for make or break contact functions.

The invention will be further described with reference to the accompanying drawing, which shows perspectively a relay made according to the invention.

A box-shaped cover is on the drawing indicated by the reference numeral 1. In the shown embodiment it is assumed that said cover is of a transparent insulating material, for example so called Plexiglas. On one side 2 of the cover there is fastened the electromagnet which consists of a bridge 3, made of a ferromagnetic material and bent to form a right angle. Surrounded by a coil and fastened to the bridge there is a magnet core 4 with a pole shoe 5 which attracts an armature 6, turnably mounted upon the bridge. An operating strip 7 of insulating material is arranged in proximity with the cover side 8 and guided for displ'aceable up and down movement in its longitudinal direction by means of pins, projecting from the cover and meshing into axial grooves in the strip. When the armature is attracted and released, the operating strip is given a forward and backward motion between its two end positions by means of an arm 9, fastened to the armature 6, which is provided at its free end with a notch'which receives the operating strip 7. The notch defining arms, one of which is visible at 10 in the figure, are flexibly connected to the operating strip 7 by means of convex stops 11a and 11b. As releasing an L-shaped torsion spring 12 functions as a release spring for the armature 6 and the operating strip 7, one end 13 of which rests in a notch 14 in a corner strip, arranged in the cover. A part 16 of the end 13 of the spring is bent at an angle, which at its free end is again bent at an angle in order to form a small projection to be inserted in either of a number of holes 17 on the rear side 18 of the cover. The torsion spring 12 passes on the front through a hole 19 through the front cover side 8, which hole functions as a bearing for the spring. A part 20 of the torsion spring 12, bent at an angle to the main part of the spring, operates upon a projecting part 21 protruding from the operating strip 7 and proceeds on to the lower side of another projecting part 22, protruding from the front cover side 8. As the little projecting part on the part 16 of the torsion spring is inserted in a hole 17, located higher up, the pretension in the part 20, effected by the torsional action, will be increased, in which case, however, the upper end position of the operating strip 7 is limited by the part 20 resting against the projecting part 22 as this forms a stop for the upward motion of the part 20. The releasing force can by this means easily be set and adjusted by turning the part 16 in relation to the part 20.

The fixed contact members consist of torsion springs in the shape of comparatively stiff wires which are arranged in pairs for each set of contacts and are designated 23 and 24 respectively. They are all L-shaped and each comprises a longer fastening arm 25, which has its end 26 firmly and against turning immovably fastened to the strip 15 and the rear cover side 18, and passes at the front through a hole 27 serving as a bearing in the front cover side 8 and, further, a short contact arm 28, which runs parallel with and before the front cover side 8. The fixed contact members 23 and 24, pertaining to the same contact pair, have their fastening arms extending on either side of the electromagnet and have their contact arms directed towards each other. The fastening arms of the contact members 23 and 24 are of somewhat different length, so that the contact arm of one contact member will .be located nearer to the cover side 8 than the contact arm of the other contact member. On the other hand, the fixed contact members 23 and 24 are located at the same height so that their contact arms will be located in substantially the same plane, which is perpendicular to the longitudinal direction of the operating strip 7. The fixed contact members 23 and 24 are suitably made of a material having good spring quality, for instance Phosphor bronze, and have the free ends of the short arm parts provided with sleeves 29 that are forced upon and soldered or welded to the wire, and which are a made of a material'with'good contact qualities, such as silver. Such fixed contact members 23 and 24 are equally spaced apart along. the length of the operating strip 7 in an arbitrary number dependent on the maximum num-- and breaking respectively of the contacts is effected by means of movable contact membersin the shape of pins 30 which, when the electrorn'agnet is operating, make or break, respectively, a'connection between the pertaining fixed contact members 23 and 24 of respective pairs The pins 30 are'inserted in holes in the operating strip 7 and pass out through a slot"31 on the-front side of the cover. The operating :strip 7 isgas-shown at the contact set A, provided withtwo 'holes '32 and 33 respectively for each set of contacts. -By inserting the pin 30 in the hole 32, as is the'case with the contact set A, a make contact function-is obtained while, if the pin 30 is inserted in the opening 33, a break contact function is instead obtained as shown at B. The location of the holes in the operating strip 7 and the end positions of the strip are so selected that the pins 30, when making contact with the fixed contact members cause acertain swinging out of their contact arms 28 so that a certain desired contact pressure arises through torsional action. The. direction of this swinging movement will be dependent upon the kind of contact functions for which the different sets of contacts are used, and the swinging movement in. the embodiment shown will consequently be directed upwards for break contacts and downwards for make contacts. Spring action ,of the fixed contact members is consequently assumed in both directions from a neutral position which, due to the fact that these contact members are formed into torsion springs,'can be obtained in the manner shown to sufl'iciently great accuracy without any after-adjustment being necessary in general. It may be of importance that the holes 27, which operate as bearings for the torsion springs, do not allow any appreciable motion of the fastening arms of the torsion springs in the motion direction of the operating strip and that the contact arms are stiff so that principally only torsional action is effective.

A number of projecting parts 34, protruding from'the front side 8 ofthe cover, are further shown on the drawing. They have their upper and lower sides 35 and 36 respectively located at such a suited distance from adjacent fixed contact members, that in case the pin 30 is I welded together with a pertaining fixed contact member,

for instance 23, the motion of the operating strip 7 is checked either when closing or breaking by the short arm part of the fixed contact member being stopped by the appropriate surface of the adjacent projecting part 34 in such a position, that the circuit between the fixed cont-act member, pertaining to the other contact pair, and said welded pin 30 is broken and also that the circuit between remaining pins 30, having the same contact functions, and their respective fixed contact members is broken without the contact pin 30, forming part of contact functions of opposite kind, being allowed to make contact with its respective fixed contact members. This special device with the projecting parts 34 is intended to meet certain safety demands which can arise when for instance the relay is used in railway signal systems, .and a thorough description of the device in question and its practical qualifications are found in U. S. patent application, Ser. No. 517,188, filed June 22, 1955.

From the above mentioned it will be observed that the different sets 'of contacts can optionally be disposed for make or break contact functions according to whether the contact pins 30 are placed in the holes 32 or the holes 33. In order that the fixed contact members when being manufactured should obtain the intended neutral position, their contact arms can be placed in a jig device before the ends 26 having yet been tightened. It has proved 4 that the tightening can then be done to advantage by aid of any suitable glue or paste.

The invention can of course be varied and modified in many different ways without giving up the principal scope of the invention. Thus, the fixed counter-contact members need not necessarily have a circular cross-section, but can instead be made as fiat-spring shaped metal strips. Further, the operating strip 7 can possibly be provided with more than two holes for each set of contact springs. In the embodiment described it is further assumed that the contact pins 30 do not have any outside electrical connection and that such connection is only obtained through connection to the ends ofthe fixed contact members 26, which are extended to soldering terminals and project through the cover side 18. However, it is of course possible to have the contact pins provided with terminals in which case they can co-operate with only one fixed contact member in each set of contacts or else they can, in the embodiment shown having'double fixed contact members, be connected as twin contacts.

In the embodiment described above it is assumed that different contact combinations are obtained by different location of the movable contact members in the operating that several different types of operating strips must be kept in stock and this inconvenience becomes particularly great if many different variations of contact combinations are to be taken into consideration.

Further, it can be mentioned that the movable contact members, made in the shape of pins or the like, can instead be directed perpendicularly to the direction in which they are placed in the embodiment described above, "in the same plane, in which case the fixed contact members can have the parts, co-operating with the movable contact members, bent at an angle-to the parts of the same which in the above have been called arms. The movable contact members will then suitably extend across the operating strip with parts projecting out on either side of the same, whereby-the contact parts of the fixed contact members of each set of contacts are located on each side of the operating strip, each co-operating with the appropriate one of the two mentioned projecting parts.

I claim:

1. In an electromagnetic relay having a reciprocating armature mounted for reciprocatory longitudinal movements between opposite end positions, an operating strip longitudinally displaceable by said armature between two end positions, fixed contact members arranged along the length of said operating strip, and movable contact members for closing and breaking the connection with said fixed contact members in response to a corresponding movement of said operating strip, said fixed contact members each comprising a torsion spring of substantially L- shape and including a contact arm and a fastening arm,

each of said fastening arms being secured against rotation at one end and connected to one extremity of the respective contact arm at the opposite end, the opposite extremity of said contact arms extending into association with said movable contact members, said opposite end of each said fastening arm adjacent to the respective contact arm being rotatably journaled relative to said one end so that a rotational movement of each said fastening arm and each said contact arm about the axis of the respective fastening arm is torsionally resisted.

2. In an electromagnetic relay having a reciprocating armature mounted for reciprocatory longitudinal movement between opposite end positions, an operating strip longitudinally displaceable by said armature between two end positions, fixed contact members arranged along the length of said operating strip, and movable contact members for closing and breaking the connection with said fixed contact members in response to a corresponding movement of said operating strip, said fixed contact members each comprising a torsion spring of substantially L- shape and including a contact arm and a fastening arm, each of said fastening arms being secured against rotation at one end and connected to one extremity of the respective contact arm at the opposite end, the opposite extremity of said contact arm extending into association with said movable contact members, said opposite end of each said fastening arm adjacent to the respective contact arm being rotatably journalled relative to said one end so that a rotational movement of each said fastening arm and each said contact arm about the axis of the respective fastening arm is torsionally resisted, said operating strip defining a plurality of longitudinally spaced apart recesses for receiving said movable contact, said recesses being longitudinally spaced apart from each other in the longitudinal direction of said operating strip, at least two of said recesses being provided for each set of contacts, each set of contacts comprising a movable member and a fixed member, a movable contact member in one of said two recesses, the operating strip when said armature is de-energized resting against said fixed contact members to establish predetermined contact pressure therewith, said movable contact member in the other end position of said operating strip being spaced from said fixed contact member, said movable contact when disposed within the other one of said two recesses being spaced from said fixed contact member when said operating strip is in the de-energized position and in the other end position of said operating strip rests against said fixed contact member to insure predetermined contact pressure, whereby each set of contacts can be optionally disposed with a set of make or break contacts by the location of the movable contact member in one or the other of said two recesses for the set of contacts in the operating strip.

3. In an electromagnetic relay as set forth in claim 2, wherein each set of contacts comprises two similar fixed contact members between which the movable contact members can make electrical connection, said movable contact members being in the form of pins.

4. In an electromagnetic relay as set forth in claim 3, wherein said fixed contact members comprise terminals for connection to electrical circuits.

5. In an electromagnetic relay as set forth in claim 4, wherein said fixed contact members comprise stiff wires.

6. In an electromagnetic relay as set forth in claim 5, wherein said fixed contact members are rotatably supported within circular openings defined by a wall, said openings having a diameter for limiting movement of the supported motions of the fixed contact members in the motion direction of the operating strip.

7. In an electromagnetic relay as set forth in claim 6, wherein said relay includes an electromagnet having a core and said operating strip extends substantially parallel to the core of said electromagnet, said contact members being fastened to portions on the side of the core that is opposite to the operating strip and being rotatably supported on that side of the core adjacent to the operating strip.

8. In an electromagnetic relay as set forth in claim 7, wherein said fixed contact members in each said set of contacts include fastening arms extended on either side of said electromagnetic core and contact arms directed toward each other and toward the respective movable contact members.

9. In an electromagnetic relay as set forth in claim 8, wherein said fixed contact members are secured and rotatably supported upon plates disposed on the two sides of the electromagnet, said plates forming the sides of the cover surrounding said electromagnet.

10. In an electromagnetic relay as set forth in claim 9, wherein said fixed contact members are provided with sleeves of conductive material, said sleeves constituting contact bodies for cooperation with said movable contact members.

References Cited in the file of this patent UNITED STATES PATENTS 803,486 Hill Oct. 31, 1905 1,521,591 Beck Jan. 6, 1925 2,106,581 UnWin Jan. 25, 1938 2,136,612 Dubuar Nov. 15, 1938 2,456,893 Roth Dec. 21, 1948 2,523,360 Ellwood -1 Sept. 26, 1950 2,630,500 Rommel Mar. 3, 1953 FOREIGN PATENTS 116,681 Australia Mar. 18, 1943 401,087 Germany Aug. 26, 1924 548,024 Great Britain Sept. 22, 1942 

